Flexible tubing



p 2, 9 w. E. MVEISSNER 2,609,002

FLEXIBLE TUBING Filed April 29, 1946 3 Shets-Sheet l W. E. MEISSNERFLEXIBLE TUBING Sept. 2, 1952 Filed A rii 29, 1946 3 Sheets-Sheet 2 w.E. MEISSNER Sept. 2, 1952 FLEXIBLE TUBING 3 Sheets-Sheet 3 Filed April29, 1946 Patented Sept. 2, 1952 -UNIT-EDL STATES PATENT OFFICE"2,609,002

"- FLEXIBLE .TUBING ,WiIIIamEEL. Meissner; Newark; NJJ.itApplication'April-zll, 1946, S1i'al N0. 6651864 ld qlaims. lfz'ifiherpresentinventionrelates'generallmtdflexilclblezztubingeandrmorexpartioularlytto'rtubinghaveaing 12a irelatively lth'in -z iwallf incorporating in: the,s'stnucture. llthereof a uhelical ireinforcement of espring immaterial.fltizalsoz c'omprehends a: novel :methcd for ."formingasuch a flexiblereinforced tubing.

iThe :t'ubing ::hithento.iavailable for: the i' transgiport' 1'gasescand' liquidsrhas. not'spossessed :the

:Zdesire li'ghtnesspflexibilityiand; adaptabilityzto izbending for thereasonvthatpin orderto provide ia'lsmoothgself-sustaining internalchanneLit :has sitbeen necessary toa'tmakezthewall' structure thickwithzthe.iresultzthatcsharp bends. areitprecludedaandeevensmoderatetberidsaareqobjec- .';tionable :becauseoi'xthe accompanying: reduction rain zcirossesectional :area. Inordinary :.flexible ttubing= of relatively :thin v wall construction:the ttoldstproduced EatEIhGiILmSide. :of a .;bend andlzbetweenfihezhelicaliiloops .of the wallmaterial tend ttoturn:orilfoldiintotthestubes space, .or' some: foldsmayzturn:inwardlyaafidwthers=outwardly. ..Everyizbend"offershydraulic'resistanoe: to fluid "flow,:andrmaterialsconstruotionof thecross sectional openzing zatzlthebendmillsin somecaseszadd such aidditional resistance casitoraprevent:the use :of ':the itubingcwhereasolidscare beingconveyed with aiiliquidtomgas.

The principalzobd ectiiofzthecinventionlis to. pro-"fyidea'lainfiwf'ialld improvedlformiof"light; flexible chiming.

linisaaegeneral;obiect;oftthis'inventionz1toprovideitkfin'ewallleckflexiblertubing thatwill be self snstaining, ilfreely -.:bendable, substantially:conr-sta-nt :intcrossesection-rwhen rbent, :and 1 readily ccollapsiblelongitudinally.

aadditional object not ELthe iginvention is 1 y to ,1providenasflexibleitubing ofwthex character mindiecateirthesloose 31118113621911 of which:along ithe :smallersradiuseofr curvaturezof a bend will :tend ittoxfold;omaccordioncoutwardly:rather thanzin- ,ai'dly; i c

eAnothercobjectz ofiithisrainvention jis"v torprovide asimple method foroonstructingshelica'lly wound'ispirahtubinghavingtascontinuous:reinforcement ,45

toil-z springelike characteristics;inisuch2a :ma-nner iasiztofinsureatautness iofiithef ithin-walledi :tubing between the reinforcingiframework.

liAistillifurtheraarid specific inventive objectrewasides':imthezprovisionof facmethod "for .makingatcontinuouswalled:r.thin::tubingr incorporating a 'irhelicalsspningelike-sreiniorcementLin: which wall-Fportions:betweenstheihelicesaof the reinforcementearezpredisposedatmbend outwardly when the tautemssepmducedcbyatherreinforcement: is relaxed. 1 "Bhe' spacingbetweenfthei-turns:ofitheispring-iwlre FEurther; novel features, of"improvementcontributing to simplicity of manufactureeande-efm 4.ciencyxiniuseiwillbelperceived and-readily under- :stood from z-a:consideration; of, the cletail'ed iderscriptionrwhioh'follows.

ziAccording ;to-ithe1 invention*-'there-.-is provided a flexible,thin-walled tubinghof spiralz-or-i any jother; continuous constructionhaving associated -with-:the:-wall thereofxa continuoushelicalreinforcement of spring-'like characteristics vaar- =:.ranged;tomaintaintheewall of the: tubing -inan extended wposition between thesuccessive l: coils of its helix and to-accommodate-simplerorcoom lplex,bending through large and @small angles whileiatwtheisame@timetmaintainingea eunifor-m internal :crossesectional larea eat theabend:bylinsuringithatithelmaj ar -portion at least of theefoldsthus;producedvextend' soutwar dly, of the tube.

,In accordance with-apreferredembodimentxof the novel method of theinvention astr-i-p of thinwalled, material is -woundnspirally= aboutamandrel of circulanoross-section which has first-been provided-witharcontinuous; convexed projection l in-the term of a helical bandextending in; the sea-me; directiomas :the -spiraL-Wound material; -A lcoiled: reinsforoing sspring of appreciable pitch inits-normallunstressed: state is applied toitheman- -,-drel a. compressedcondition, maintained bypa i-groove defined by -the helical band,v and,over. the vinnerllayer of thetubing wall. Aftereanouter .layeriof wallmaterial ,is applied over sthelreinforcing spring uthe/seamsv ,oftheinner layer of wall materialare. sealed, the outer .layer ofspringccvering. materialand the innerJlayer. of mate- Urialarebondedorsecured together, and thenow ;.,impervious tubing removed from themandrel,

whereuponitrwill assume a formpin which the springgreiniorcingflisextended and. the" material between thesucoessive .coils of thesp'ringwill be stretched out taut. '.The wall ',material between the sp'ringcoils. which has been arch formed over the continuous projectionxproyided by the -hel ical, band will have a tendency to returntotheshape ;of an 'outwardly extending loop when the spring is compressedwhile the tubing is in use. 7 This combination of advantageous resultsde- -rives fromthe characteristics of -a=spring-wlre *helix'havingenough space between its to "permit compression. When this typeof spring iscompressed a continual force is exerted tending to restore-'-theoriginal-free state or pit'ch. "iwhatever change in "diameterresults" from" com- :pression is in the direction of increased.diameter, whether ":'the "helix .=is istraightor 'cu'rved.

helix must also be correlated to the diameter and wall thickness of thetubing in such a manner as to accommodate flexing of the wall materialaway from the helix.

For a more complete understanding of the nature and objects of theinvention reference is made to the accompanying drawings in which:

Fig. 1 is a side elevation of one form of the tubing employing a doublehelical reinforcement;

Fig. 2 is an end view of the tubing illustrated in Fig. 1;

Fig. 3 is a somewhat enlarged side elevational view illustrating thechange in the configuration of this tubing when bent through an angle ofapproximately 90 degrees;

Fig. 4 is an enlarged longitudinal sectional view of a fragment of thetubing shown in Fig. 1 illustrating a method by which it may be formed;

Fig. 5 is a similar longitudinal section showing the shape normallyassumed by the tubing after formation;

Fig. 6 shows in fragmentary longitudinal section the details of theshape assumed by the inner curved portion of a length of tubing havingthe construction of Figs. 4 and 5, when bent through an angle of 90degrees;

Fig. '7 is a fragmentary longitudinal sectional view illustrating amethod of forming a modified tubing employing a single helicalreinforcement; Fig. 8 is a similar longitudinal sectional view showingthe shape normally assumed by the modifled tubing after formation; and

Fig. 9 shows in fragmentary longitudinal section the details of theshape assumed by the inner curved portion of the modified tubing whenbent through an angle of approximately 90 degrees.

In the preferred and illustrated embodiment the wall structure of thetubing is formed of an at least partially transparent material havingelastomeric or rubber-like properties. Such materials are readilyformable, have good resistance to abrasive and corrosive action, and arehighly impervious to gas and liquids. The invention is not restricted,however, to the use of elastomeric material, as cloth fabric whichhasbeen impregnated, or coated, or laminated with such material, to make itimpervious to gases and liquids may also be advantageously used. Byreason of availability, and because it posse ses the required 'basiccharacteristics in a high degree, the commercial forms of thermoplasticfilms or sheets of vinyl resins are particularly desirable. Accordingly,this invention will be described with particular reference tothermoplastic sheets or films of. the vinyl base type such as aremanufactured and sold by Carbide and Carbon Chemicals Company under thetrade name Vinylite. Thermoplastic resins such as these may be bonded orsealed in a variety of well known ways including singly or cojointly theuse of adhesive, vulcanizing. pressure and heat.

The requirements for the framework of the tubing, comprising a distentedhelix of spring-like material, are best satisfied by a metal spring wireor strip of stainless steel, although there are wide ranges of commonlyused materials and protective finishes which may be suitably employedfor the purpose.

' In its basic aspects the tubing of this invention comprises a thinflexible inner wall, an encircling spiral reinforcing spring, and anouter covering for the spring secured to the inner wall so as toprovidea continuous spiral sheath or pocket formation which may turnabout the spring as the tube is bent and corrugations formed. For someapplications of the invention it may be preferable to provide anadditional flexible armor coating over one or both sides of this basictubin construction.

Referring to Figs. 1, 2 and 3, the numeral I0 indicates the flexibletubing in general, including a relatively thin inner. wall I2 formedfrom a sheet of thermoplastic material and a double helix form of metalspring I4 covered by a thin flexible outer layer or wall ofthermoplastic material It.

It will be observed in Figs. 1 and 5 that the pitch of the double springI4, which is shown in its normal extended position, is substantiallygreater than the distance between its adjacent parallel coils and thatthe correspondingly spanned portions I8 and 26 of the tube walls aremaintained in a taut position that provides a smooth surface within thetubing.

When the double helix form of tubing construction I 0 is given a simplebend through an angle of degrees, as indicated in Fig. 3, the longerunsupported wall sections or loops .I 8 will-be caused to fold outwardlyat the inner side of the curve as best illustrated by the fragmentarylongitudinal section of Fig. 6. In this particular embodiment there willbe a minor reduction in the crosssectional area of the tubing I 0 due tothe inward projection of the loops formed by the shorter wall sections20 extending between the adjacent parallel coils. This reduction incross-sectional area will amount to less than 5 per cent, which is morethan compensated for by the added strength and resistance to a superiorexternal pressure afforded by the second of the helix coils. In thisconstruction the folding of the, one loop complements and helps thefolding of the one next to it and each strengthens the other since theypivot in pockets 22 around the round wire of the helix coil I4. It isdesirable that the infolding section or loops I8 be as narrow aspossible. This result is achieved in the illustrated embodiment byspacing the two parallel helixes a distance less than half the pitch ofthe double coil spring in extended condition;

When the wall is of elastomeric material the loops 20 on the outer sideof the curve can stretch to some extent in accommodation.

The method of forming and constructin the double helix tubing of Fig. 1is illustrated in the enlarged fragmentary longitudinal sections ofFigs. 4 and 5. The inner layer I2 of wall material is spirally woundaround a hollow cylindrical mandrel M having a continuous, convexcrosssectional protuberance P formed by aconstant pitch helical band Bhaving a flat inner surface in continuous engagement with the mandre1 M,the spacing between adjacent edges of successive turns of band B beingslightly greater than the spacing between the remote edges of adjacentparallel coils of the doubl helix spring I4. The arrangement is suchthat the overlapping seams 24 of the inner wall layer I2 occur at thetop of every other turn of protuberance P. In other words, the width ofthe inner layer I2 spiral is approximately twice the distance betweenthe helical bands B providing the protuberance P.

The outer layer I6 of wall material is spirally wound in the samedirection over the inner layer I2 and the double helix reinforcingspring I4 so that the width of the strip forming layer I6 and the pitchof its overlapped edges or seams 26 corresponds to the pitch of thedouble helix and the overlapping comes over successive turns of the sameheli-x inert-Be 'the 'joint ifiillow one ofiitheecorrstantly pacede'l-iXes comp'r -is'ingbthe eubllielixrein-forcement' "I 1 ---Dur'ng theadhering or securingdfithe two wall by having the-dimension- =of=-thewall material mover-1 the o-turns of I. -protuberance iP measured innormal pitch direction, approximately.-=equalato the similarlymeasureddistance between the more widely spaced;-'afdjacent-coiis of the springl4 in extended condition. Preferably this dimensionaz'of Qthewalla-material is made-slightly less-. torit-insurestautnessvbwpermitting only, ,partial releasej'ofa the iC mpITBSSiQnoisprin j l: I l 1 'Si'l'h'e' manner of forming rthec'continuous scoil,sPOGZKEBSgQrqrShGdllhS ,2 2 ,deservesispecial :consideraetion becauseof the effect itzhasin producing :inzebendingioftthe shorter lpps;20\(Fig. 6). lReferfling tothecross section of-%l={ig.l 5;it will:be:-notedgzthatztheimajor and outWard-lymurved partiof. the

pocket 22 is formed by the outer wall layer IS, with very little or noneof the double wall thickness between adjacent, closely spaced coilsextending above a generally horizontal line connecting the centers ofthose coils. Consequently, when the tubing I0 is bent to the angular portion of Fig. 6 with the spring I4 compressed on the inner side of thebend, the loops will be impelled inwardly and will not assume a positioninterfering with full compression of adja cent closely spaced springcoils. The pivotal action of pocket 22 assists in this desired result.

A modified form of tubing construction is illustrated in the fragmentarylongitudinal sections of Figs. '7, 8 and 9. Essentially thismodification comprises a tubing indicated generally as and comprising aninner layer 32 and an outer layer 34 of elastomeric material similar tothat described with respect to the principal embodiment. These walllayers 32 and 34 enclose the spaced coils of a single helix or metalspring 36 in a continuous spiral pocket or sheath 38 formedtherebetween.

In forming the tubing 30 the inner layer 32 is applied around acylindrical mandrel M having on its outer face a helical, convexcross-sectioned protuberance P with nearly contiguous turns constitutinga helical band B having a flat inher surface engaging the mandrel M. Therelatively small space between the turns of protuberance P receive thereinforcing spring 36 in longitudinally compressed condition and withinthe pocket formation 38.

Preferably the inner layer of wall material 32 will be a continuousenvelope such as may be formed by helically winding a strip of suitablewidth elastomeric, thermoplastic material around the mandrel M so thatits adjacent edges abut and the seamless joints 40, which may be sealedby fusing, will have the same pitch as the spring 36 in its extendedposition and will fall midway 'Z an'd' l6" 0 eachother and attheiriseams between .th lrsuccessiyenidils thereof. 'flihe'ealsorcontinuous: :ou-ter zwallrlayersfl :maySEb e? similarly izfomnedufrom a:s'pira'l1ycwound"strippofziiheisaine composition, width and pitch asthe layerz32gzbnt i'preferablyi:imstaggerederelation.:.thereto:so:3i;hataitsrjni'ntsi42:will:coincideawith'jthersuccessivacnils of the spring 36whemthe' 'latterzisifullyiexteriddinitial; compression: or longitudinalexpansi- --bility:,.of:jthe spring :3 fi'swill :bezat 'leastzsn'ificientI0 1 tor-stretch: out. the wa-llw layers; :32; and 1 3451150 tithestr'aight condition.shownrinsliigeii; aParticular note is.:made thatain'Eig.:9,s.show- ,z'lllg :theinnerj: curved section:ofeaniapproximately I5-15 stiallyw :no constrictiomof fthe cross-,sectionalrareaatethezbendwdue to -th r fact that-the single-v folds 42 :of; availmaterial; all; extend completely outward nf-the tubing.vwhiieeasr-was.indicated. heretorfore, thee single .=helix..-reinforced. tubing J30 -.wi ll 2o shave-lesser folding strength-than the.doublezehelix =.;form,:it1 will beefound more;advantageousawhere.nos-internal.constriction .at bends: is permissible and where .the.pressurewithin t the. 'fb'llbBsflZiGEdS .thatwithout, 25 ,lntboth the.double helix-. formeoflEigs l-: to.-.-6 nand thesingle helix formof:F-igs. (7,; 8;.andi9 the manner ofsforming sor shaping. the? tubingwall .,material. over spaced-:convexedgprotuberances of a. mand-re1predisposes ;the v.-n1ateriall-between.tl'ie '30 rhelixes to .bending101 "looping radially-eoutwar'd .when the. tubing issturned .throughantang-leeor 4 compressedlso-as toreleaserthe tautness produced by thespring reinforcement. ,eln theacaseeof' the double :hGl-lX tubing this.-inherent-,- predisposition I :ofthe longenloops; 4 fliaids the.radialinbendine of the shorter loo ps28,which arenotiormedmver convexedprotuberances but have, nevertheless, an inbending tendency for thedifferent reason previously explained.

From the foregoing detailed description of two embodiments of thisinvention it will be seen that there has been provided a flexible tubingthat is extremely light, of minimum bulk, and which possesses therequired tensile strength and re- 45 sistance to flow conditions tosatisfy the conditions previously enumerated. Among its additionaladvantages are the fact that it will remain physically constant over awide temperature range degrees to 170 degrees F., will withstandpulsations and vibrations, and, most important of all, can readily bebent through as much as 180 degrees to a radius of curvature equal tothe diameter of the tubing and Without material reduction of itscross-sectional area in any part of the bend.

Depending upon the desired conditions of use, the tubing of thisinvention may obviously be made of a number of other known materialshaving the general properties indicated as essential.

When made of vinyl resin polymers, the wall of this tubing canconveniently and inexpensively be made transparent or apaque, and by useof any desired color or colors serve both decorative and identificationpurposes.

There are a large number of different uses for the improved form offlexible tubing provided by this invention. A few random applications ofimportance are: air conditioning ducts, tubing for blowers or vacuumsweepers, speaking tubes, and, in general, to the solution of allrelated tubing problems involving the flow of liquid or gases eitherwith or without contained solid material.

Since this invention admits of a number of modifications in the specificmaterials employed aeoaooa "and vthe details of tubing manufacture andconand bendable tubing comprising a flexible resilient tubular wallformed of at least two layers comprising a thermoplastic material, areinforcing strand forming a helix of widely spaced courses coaxiallydisposed between said layers, the layers being bonded together betweensaid courses to anchor said helix therein, and constituting a continuousspiral wall between courses of said helix, said Wall having therein astress normally biasing said wall into an arch of decreasing radiusbetween said courses of said helix when said wall of said tubing isdeformed whereby the direction of fiexure of said wall arches said wallin a predetermined direction when said tubing is compressed or bent.

2. A tubing as recited in claim 1 in which the arch of the spiral wallarea between courses is convex so that said wall area folds outwardlywhen the-tubing is compressed or bent 3. A tubing as recited in claim 1in which the wall is formed of two strips of thermoplastic material, theedges of each strip forming a spiral seam with the edges of the spiralseam of the inner strip being spaced longitudinally from that of thespiral seam of the outer strip.

- 4. A tubing as recited in claim 1 in which the helix is formed of twoseparate strands arranged in spaced parallel spiral courses.

8 5. A tubing as recited in claim 1 in which a second helix is enclosedbetween said wall layers in spaced parallel coaxial relation with thefirst helix, adjacent courses of the two helixe being closely spaced ascompared with the spaces between successive courses of either helixthereby defining alternate narrow and wider spiral wall areas, the innerwall layer of said narrow areas lying substantially within the innercircumference of said helixes, and said wider wall areas having thereina stress normally biasing said wider wall areas into arches ofdecreasing radius when said wider wall areas of said tubing are deformedwhereby the narrow areas fold inwardly and the wider areas foldoutwardly in a predetermined manner when the tubing is deformed.

WILLIAM E. MEISSNER.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 1,736,106Williamson Nov. 19, 1929 1,797,193 Kimmich Mar. 17, 1931 1,810,032schulthess June 16, 1931 2,047,770 Davis July 14, 1936 2,245,758Chernack June 17, 1941 2,272,704 Harding Feb, 10, 1942 2,299,520 YantOct. 20, 1942 2,321,064 Broedling June 8, 1943 2,396,059 Roberts Mar. 5,1946

